Aristotle’s Psychology

Aristotle studied in Plato’s Academy for 20 years, from its founding (c. 347 BCE) until Plato’s death (c. 347 BCE). His father was personal physician to the Macedonian king Amyntas II, father of Philip II and grandfather of Alexander the Great, whose teacher Aristotle became.

Though a devoted admirer and friend of his great teacher, Aristotle departed from Platonic philosophy in the range and details of his inquiries and in the mode of inquiry. His classical formulation of psychic processes in On the Soul has often been relied on to the neglect of his other works. However, any attempt to comprehend his remarkably complete and systematic psychology requires a generous sampling from many of his treatises, including those devoted to logic, ethics, politics, and metaphysics.

What is found through such an examination is a commitment to a distinctly ethological approach to psychological processes and phenomena. Aristotle attempts to identify the essential or defining properties of a given class of animal, link these to their special tasks and the pressures faced, and then explain the given form of life in terms of its successful adaptations. In both his History of Animals and Parts of Animals the accounts offered are entirely naturalistic, and his descriptions are often exacting and comprehensive. The teleological character of the accounts is often quite similar to what one now routinely encounters in contemporary ethological texts (though Aristotle, unlike Em­pedocles, did not explicitly advance an evolutionary theory).

In the treatise On the Soul Aristotle sets out to offer an account that is to be, in his words, fully “compatible with experience,” avoiding the famous Socratic dialectical method. The first chapter treats both emotion and sensation as conditions of the soul that can only exist through the medium of a body. All such affections of the soul are to be conceived as derived from the body. This essentially physiological character of his psychology appears throughout his works, including those not directly concerned with psychological matters. In his Physics, for example, he argues that the affairs of the soul are brought about by alterations of something in the body. His teaching on sleep and dreams (De Somniis) again accounts for the phenomena by appealing to sensory-biological processes. Memory, too, is treated in purely biological terms. In On Memory and Reminiscence, he takes the act of recollection as the “searching for an image in a corporeal substrate” and explains the memory deficiencies of children, the aged, and the diseased in terms of biological anomalies. It is doubtful that Aristotle was a thoroughgoing materialist, however, for in various places he specifically distinguishes soul from the rational mind, the latter dwelling somehow within the soul but, unlike the soul, being imperishable.

Aristotle’s theory of psychic functions covers the range from nutritive and reproductive processes to abstract rationality. The various powers (dunameis) or faculties of the soul differ in different species. The dividing line between the animal kingdom and all else is marked off by the power of sensation, this function being, says Aristotle, part of the very definition of “animal.” Indeed, Aristotle subsumes a number of psychological functions, some quite complex, under perception. As a result, although he reserves abstract rationality to adult human beings, he grants nonhuman animals wide-ranging cognitive, emotive, and motivational states and dispositions.

Rationality carries with it the unique capacity for deliberated choice (prohairesis) on which the moral virtues depend. Accordingly, only those in possession of such rational power can be authentically courageous, magnanimous, just, and so on. But the nonhuman animal community offers attenuated examples of these attributes, such that the division between human and nonhuman psychology becomes less sharp the more widely one reads in Aristotle’s surviving works.

Aristotle’s theory of perception also emphasizes sensory integration, a process that is itself not sensory. Con­sider a cup of coffee. It is a hot, lightly sweetened, dark brown liquid. The various specialized sensory organs respond respectively to each of these attributes: the temperature, taste, color, and consistency. But the experience is not of separate attributes. Rather, there is a whole, fully integrated experience such that coffee becomes distinguished from any number of other stimuli that also happen to be dark, hot, sweet liquids. In addition to the classical five senses, then, there is also a common sense (koine aisthesis; sensus communis) by which experiences are forged out of the separate contributions from the different sense organs.

After rejecting the Platonic theory of natively possessed “true forms” in Book 2 of On the Soul, Aristotle considers how the mind comes to comprehend universal propositions that could not be given in experience. His solution calls for a distinction between the actual and the potential: mind has the potential for such comprehension, but for this to be actualized, it must be acted upon by the world. What the mind thinks must be in the mind, he says, as characters can come to be on a wax tablet on which as yet nothing has been etched. As a composite of complex processes, mental life must be supplied with information, else there would be nothing for the perceptual-cognitive processes to work on. Thus, the external world must cause physical responses in the sensory organs, these responses coming to depict or represent or stand as codes for the objects that cause them. Sensations set up certain motions within the soul. These subside in time but, if they have been produced often enough, they can be recreated, or at least a likeness of them can be re-created under comparable conditions. Through repetition (by custom or habit), certain movements reliably follow or precede others. Attempts to recall past events are only attempts to initiate the right internal events. This is why, when attempting to recall a sequence of events or objects, one must find the beginning of the appropriate series. When successful, an entire train of previously established associations is set in motion.

Of course, Aristotle knew that comprehensive scientific knowledge is not possible through mere acts of perception. He underscored the particularity of every such act and contrasted it with “that which is commensurately universal and true in all cases,” which cannot be thus perceived. An understanding of the latter calls for standards of truth of an essentially cognitive nature by which mere facts become integrated into systematic bodies of knowledge. It is only through what Aristotle called demonstration that such knowledge becomes possible. Scientific knowledge is demonstrative in the sense of rational or logical demonstration. Such demonstrations are grounded in the syllogistic modes of argumentation that he invented. The major premise in such an argument may be a law of nature, the minor premise a fact of nature, and the conclusion a necessary and demonstrated conclusion. There is a certain kinship between this feature of Aristotle’s philosophy of science and the nomological-deductive model defended in modern times by Karl Hempel and others.

No figure from antiquity until the seventeenth century would be as important to the history of psychology as Aristotle. His most general contribution was to locate the intellectual and motive features of mind in the natural sciences, while reserving the moral and political dimensions of human life to a much enlarged conception of nature itself. At the level of basic processes his psychology was biological and ethological, grounded in considerations not unlike those that Charles Darwin would develop centuries later. If his own version of empiricism did not go so far as to submit scientific truths merely to confirmation by the senses, it did establish the validity and importance of the world of sense. In the process, he presented the senses themselves as objects of study. He also proposed the first laws of learning, loosely drawn around the principle of association and fortified by principles of reinforcement. Except for his retreat toward a somewhat fatalistic hereditarianism in the Politics, he consistently emphasized the part played by early experience, education, practice, Habit, and life within the polis itself in the formation of the psychological dispositions. In this way, he presented human psychology as a developmental subject whose parent science was at once civics and moral philosophy.